Infants and other incontinent individuals wear disposable absorbent articles such as diapers to absorb and contain body exudates discharged from the body, particularly urine. Absorbent articles function to contain the discharged materials in isolation from the body of the wearer on one side, and from the wearers garments and/or bedding on the other. Absorbent articles are well known in the art and are typically constructed from a combination of liquid and vapor pervious and impervious materials which respectively allow the passage of liquid into the diaper and prevent its exit therefrom.
It is known to fasten a diaper about the body of a user using a variety of fasteners having a fastening material such as adhesive or a two part hook-and-loop type (i.e. Velcro). These fasteners are typically located at a front or rear portion of the diaper, such as a flap or wing, and are oriented to engage a “landing zone” on an opposing portion of the diaper. For an adhesive fastener, a release strip may be used as a landing zone; a Velcro fastener requires a special looped landing zone.
U.S. Published Patent Application No. US 2003/0004490 A1, issued to Larsson et al. discloses an absorbent article such as a diaper having a landing zone arranged on the front or rear portion of the product and at least one hook-bearing tab arranged on the front or rear portion of the product and at least one hook-bearing tab for detachable interaction with the landing zone. The landing zone includes both active areas, to which the tabs can be fastened, and inactive areas which will not adhere to the tabs. Particularly, the landing zone is a continuous support strip with an inactive area connected between two active areas. This enables two landing zones to be formed in one manufacturing step, from a single strip.
It is also known to make a diaper having Velcro-like hooks as one component of a fastening system and a nonwoven outer surface which serves as the other component. In such a diaper, the hook does not require a special landing zone having special loops. Instead, the entire outer surface of the diaper or brief can function as a landing zone for the hooks. This is known as a “loopless” fastening system, and provides an increased degree of flexibility in the fitting of a diaper to a person. Such a loopless fastener system is described in U.S. Patent Application Publication No. US 2003/0220626 A1 filed on May 7, 2003 and is hereby incorporated by reference.
Although such a loopless fastening system is more convenient for the user, there may be a tendency to take advantage of the unlimited landing area provided by loopless fasteners to use diapers that are not properly sized to the wearer. Particularly, diapers that are too large may still be nominally fitted to an individual due to the ability of the loopless fasteners to gather in the slack created by the oversized diaper. This practice is wasteful as larger diapers are likely to be more expensive, and require more material to manufacture.
U.S. Pat. No. 5,387,208 issued to Ashton et al. on Feb. 7, 1995 discloses an example of a diaper employing a plurality of layers of pervious, absorbent and impervious materials. Particularly, Ashton et al. discloses a pervious body facing top sheet and an impervious garment facing backsheet sandwiching a plurality of layers of variously liquid pervious and absorbent material. The liquid impervious backsheet extends beyond the dimension of the top and intervening layers, thereby providing laterally extending tabs which can be joined about the waist of the wearer to hold the diaper in place during use.
Although such backsheets do prevent liquid from passing through the diaper, the impervious nature of the backsheet, often a polyethylene film, also prevents the passage of air and water vapor, resulting in a diaper which can feel hot and uncomfortable to wear.
Backsheets which are pervious to vapor are generally known as breathable backsheets and have been described in the art. In general, these backsheets are intended to allow the passage of vapor through them while retarding the passage of liquid. For example, U.S. Pat. No. 3,156,242 issued to Crowe, Jr. on Nov. 10, 1964 teaches the use of a microporous film as a breathable backsheet. U.S. Pat. No. 3,881,489 issued to Hartwell on May 6, 1975 teaches a breathable backsheet having two layers, the first of which is a thermoplastic film and the second of which is a hydrophobic tissue.
While perforated backsheets may provide improved breathability over an impervious backsheet, the materials are of limited utility as they may require multiple layers of materials to prevent leakage. Fundamentally, perforation of otherwise impervious films achieves a measure of breathability at the expense of the material's ability to resist the flow of liquid, particularly when a diaper is subjected to the normal forces created by the wearer during use.
A modified approach is disclosed in U.S. Pat. No. 5,628,737 issued to Dobrin et al. on May 13, 1997, which provides a diaper having an impervious backsheet which extends laterally beyond the dimensions of the absorbent core and top sheet on the diaper wherein only the side panels are provided with perforation, thereby providing an impervious region adjacent to the core and a breathable region which permits some movement of vapor therethrough. This approach creates a zone of liquid impermeability where leaks would otherwise be most likely to occur in the backsheet, and provides a breathable region where leaks are less likely, e.g. where the backsheet comes in direct contact with the skin of the wearer.
Although the creation of zones of permeability in a diaper resolves some of the problems which are inherent to the backsheets of the prior art, the perforation of even an isolated region of a plastic film backsheet presents its own shortcomings, particularly due to the inherently impervious character of plastic film. For example, an impervious side panel having relatively large or many perforations may achieve the desired breathability, at the expense of the material strength in the perforated zone. Conversely, side panels having relatively few or small perforations may remain strong, yet provide insufficient breathability to ensure the comfort of the wearer. Basically, the shortcomings of the prior art stem from the attempt to make an impervious material selectively behave like a pervious material. Particularly, when this is attempted on a plastic film, the result cannot be accomplished without undermining the plastic film itself, where increased breathability comes at the expense of the material's desirable properties.
An additional disadvantage of the disposable diapers of the prior art is that extensive use of impervious material, typically plastic films, is environmentally detrimental as these films are known to be non-biodegradable. The introduction of perforations into otherwise impervious films as suggested in the prior art does not render these substances environmentally friendly. The environmental consequences are above and beyond the other economic disadvantages consequences of present diaper designs, particularly that the use of multiple layers of material and the application of the complex manufacturing techniques necessary in current diaper designs render these approaches more costly than necessary to manufacture and therefore less economical to purchase.
Finally, the use of a plastic film as a backsheet precludes the use of a loopless fastener system because a plastic film cannot function as a landing zone for a loopless fastener.
Another approach to creating a disposable absorbent article having breathable side panels is found in the Prevail® version of protective underwear manufactured by First Quality Products, Inc. of McElhattan, Pa. The brief comprises a nonwoven pervious backsheet having an absorbent assembly attached thereto. The product crotch areas are provided with elastic bands sandwiched between the backsheet and an additional layer of nonwoven material. Thus, the side panels are generally pervious, although breathability is impeded by the multiple laminated nonwoven layers, and the adhesive that laminates them. This construction is similar to the Per-Fit® version of diaper, also manufactured by First Quality Products, Inc. which provides increased breathability in side panels comprising two laminated layers of nonwoven material, and is subject to the same drawbacks.
Therefore a need exists for an absorbent article such as a diaper having a fastening system which prevents improper sizing of oversized diapers.
A further need exists for an absorbent article such as a diaper having an absorbent core capable of absorbing and retaining fluids, while maximizing the breathability of the article.
A still further need exists for an absorbent article which minimizes the use of fluid impervious and/or non-biodegradable substances.